Variable pitch propeller for airplanes or the like



S. M. ALLR ED April 5, 19384.

VARIABLE FITCH PROPELLER FOR AIRPLANES OR THE LIKE vFiled July 8, 1935 QQ N Patented Apr. 5,' 1938 UNTD VARIABLE FITCH PRPELLER FOR. AIR- lPLANES R THE LIKE 18 Claims.

'I'his invention relates to a variable pitch propeller for airplanes orthe like and more particularly to such a propeller in which the pitch`angle of the blades is controlled by fluid operated mechanism. It hasbeen proposed heretofore to provide hydraulically controlled blades in apropeller but in these propellers the hydraulic mechanism has, for themost part at least, been mounted exteriorly of the propeller hub and wasof a more or less complicated character. As a result it offered anincreased air resistance, interfered with the proper balancing of 'thepropeller and was subject to injury by impact and vibration.

One object of the invention is to provide a propeller in which the pitchangle of the blades will be controlled by fluid operated mechanismlocated wholly within the propeller hub.

A further object of the invention is to provide such a propeller inwhich the uid operated mech- 0 anism will be of such a character and soarranged that it will not interfere with the proper balancing of thepropeller. e

A further object of the invention is to provide such a propeller inwhich the pitch angle of the several blades will at all times be thesame and in which the blades will be rotated to change the pitch anglesimultaneously and. to the same extent.

A further object of the invention is to provide such a propeller inwhich the blades may be adjusted through a relatively wide angle.

A further object of the invention is to provide such a prcpeller whichwill be simple in its construction and of a strong durable character.

A further object of the invention is to provide such a propeller withblade bearings of a character which will withstand the severelongitudinal and transverse strains to which they are subjected.

Other objects of the invention may appear as the structure is describedin detail.

In the accompanying drawing Fig. 1 is a transverse section taken throughthe propeller hub on the line I-I of Fig. 3 and partially broken away;Fig. 2 is a longitudinal section taken through the propeller hub on theline 2-2 of Fig. 3, and partly broken away; and Fig. 3 is a -transversesection taken on the line 3-3 of Fig. 1.

In the drawing I have illustrated one embodiment of my invention andhave shown the same as applied to a three blade propeller but it will beunderstood that this particular embodiment has been chosen for thepurposes of illustration only, that the mechanism may take various formsthe gear I I and, through this gear and the pinions (Cl. 17o-163) andmay be embodiedl in propellers of various kinds.

In the particular construction here illustrated the propeller comprises`a hub having a tubular inner portion 5 adapted to receive the driving 5shaft, and a plurality, in the vpresent instance three, blade socketswhich are carried by and project radially from a housing I arrangedabout the tubular member 5 of the hub Aand spaced from the intermediateportion thereof. The hub is preferably divided transversely to its axis,as shown in Fig. 2, to facilitate the assembly thereof and the two partsare rigidly connected one to the other, as by bolts 8. The propellerblades are mounted in the respective sockets 6 for rotatory movementtherein, the shanks only of the blades being shown at 9.

The several blades are connected one to' the other to cause the same torotate in unison and to maintain the same at the same pitch angle 20 andsuitable fluid operated mechanism is mounted Within the hub andconnected with the blades to control the rotatory movement thereof, thisuid p operating mechanism being preferably connected With the meanswhich connects the blades one to the other.

As here shown, the shank of each blade has secured thereto a beveledpinion I 0, the hub of which is, in the present instance, screw threadedonto the inner end of the shank. Each pinion Il) meshes with a beveledgear I I rotatably mounted about a portion of the tubular member 5 ofthe hub and having an elongated bearing I2 provided near its inner endwith a circumferential ilange I3. .The uid operated mechanism may takevarious forms but preferably comprises a plu-l rality of substantiallyradial cylinders projecting from the housing 'I of thelhub. )Preferablythese cylinders correspond in number to the blade sockets and arearranged within the respective sockets. In the construction shown, theblade shanks 9 are tubular and cylinders I4 are fitted snugly lwithinthe respective tubular shanks, and rigidly secured therein, asl by angesI5 clamped between the inner ends of the blade Shanks and shoulders I 6on the pinions I0. The out/er end of each cylinder is closed and mountedin each cylinder is a piston I'I which is connected' with one or more ofthe blades. Preferably each piston is connected with all the blades andthis may conveniently be accomplished `by connecting the same with theflange I3 of the gear Il by means of connecting rods I8. Therconnectionsare of such a character that all the pistons will act upon .pilot in anysuitable or well known manner.

I 0, on the-several rotatable blades. Fluid under pressure, such as oil,maybe supplied to the outer portions of the cylinders, beyond thepistons, in any suitable manner, and,.in the present instance, conduits,such as rigid pipes I9, extend through the respective pistons into theouter portions of the cylinders and are connected at their inner endswith the tubular member 5 of the hub. Each pistonA is slidably mountedon its conduit I9 and means are provided for preventing the leakage ofthe fluid through the piston about the pipe, such as the sleeve 20 andpacking 2|. The tubular member 5 ofthe hub is'provlded withlongitudinally extending passageways 22, each of which communicates withthe inner end of one of the conduits I9. These passageways 22 extendbeyond the rear side of the housing and are provided with ports 23 bymeans o1' which they communicate with an annular channel 24 inastationary collar 25 mounted about the inner portion ofthe tubularmember 5 of the hub. 'I'he collar 25 ts snugly about the end of thetubular member 5 so as to prevent the escape of uid from the channel 24and if it is desired suitable packing may be interposed between thestationary and movable parts. A supply pipe 25a leads from the annularchannel 24 to a suitable source of fluid under pressure, preferably anoil pump, the operation of which is under the control of the Inasmuc asthe pump constitutes no part of the y present invention and the fluidmay be delivered to the apparatus from any suitable source of.y

supply the pump is not illustrated.

The blade sockets 6 are of an internal diameter somewhat greaterthan theexternal diameter of the blade shanks and a suitable bearing 26 isvinterposed between each shank and its socket.

This bearing is subjected to very severe strains both longitudinally ofthe blade and transversely or radially thereto and in order thatl it maywithstand these strains and provide a free running bearing for the bladeI prefer to construct it of a series of separate ball bearing units 21superposed one upon the other, the innermost unit being supported by theen'd of the hub of the pinion I0 and the outermost unit contacting witha suitable stop device, such as an internal collar 28, in the outer endof the blade socket. In this manner the bearing also serves to lock theblade in the socket. Each bearing unit comprises two separate parts eachof which is provided with a ball race, as shown'at 29 and 30, and theseball races are arranged in a line oblique to the axis oi' the blade. Theb all rac`es are so shaped as to provide opposed contact surfacesarranged in a line extending lengthwise of the blade and other opposedcontact surfaces arranged in a line extending transversely to the blade,whereby the balls 3|, mounted in the races, strongly resist eithertransverse or longitudinal thrusts of the blade. In the constructionshown each ball race has a contact sur'face extending transversely tothe race through an arc of approximately ninety degrees and on such aradius that the balls Will contact with substantially the entire area ofthat surface, but, if desired, the intermediate circumferential portionof the surface may be out away 0r relieved to reduce friction. By thisarrangement of superposed bearing units the stresses are divided andeach bearing unit receives only its proportional share of the total loadimposed upon the bearing as a whole.

When the propeller is in operation centrifugal force will tend to movethe pistons outwardly and thus, throughthe connecting rods I 8, gear IIand pinions III, rotate the blades in a direction to increase the pitchthereof. This outward movement of the pistons is, however, resisted bythe uid in the outer portion of the cylinder and the amount'of this:duid and hence the amount' of movement imparted to the pistons may becontrolled by the pilot. When the pitch of the blades is to be decreasedfluid under pressure is admitted to the cylinders to move the pistonsinwardly and thereby rotate the blades about their axes in a directionto decrease the pitch thereof. In this manner the fluid operated devicecontrols the movement of the blades in both directions. It will beobvious, however, that by reversing the connections the movement of thepiston by centrifugal force could be caused to decreasethe pitch of theblades and the uid pressure utilized to increase the pitch of theblades. The character of the mechanism permits of a relatively longmovement of the connecting rods which, in the present arrangement, issuflicient to move the gear vII through an arc of approximately ninetydegrees, thereby providing a wide range of adjustment for the blades.

While I have shown and described one embodiment of my invention I wishit to be understood that I do not.desire to be limited to the detailsthereof as various modications may occur to a person vskilled in theart.

Having now fully described my invention, what I claim as new and desireto secure by Letters Patent, is:

1. In a variablepitch propeller lcomprising a hub having means forconnecting the same with a vshaft and having a plurality of bladesockets, and blades having shanks rotatably mounted in the. respectivesockets and heldl against radial movement therein, fluid operatedmechanism mounted within said hub and comprising a radially movablemember controlled in part by centrifugal force, means for operativelyconnecting said movable member with all of said blades to impart rotarymovement thereto and for causing said blades to rotate in unison, andmeans for supplying fluid under pressure to said uid operated mechanismto oppose the action of centrifugal force on said movable member.

2. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks rotatably mounted in the respectivesockets and held against radial movement therein, a device connectingsaid blades one with the other to cause them to rotate in unison, aseparate fluid operated device associated with each socket and mountedin said hub,

each fluid operated device having a radially movable member controlledin part by centrifugal force and operatively connected with said bladeconnecting device to cause the latter to impart simultaneous rotarymovement to said blades, and means for supplying fluid under pressure tosaid fluid operated devices.

3. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks rotatably mounted in the respectivesockets and held against radial movement therein, means for rotatingsaid blades including a device connected with all of .said blades tocause them to rotate in unison, a plurality of substantially radialcylinders carried by said hub, pistons mounted for reciprocatorymovement in said cylinders, means for operatively connecting each ofsaid pistons with said blade connecting device, and means for supplyingfluid under pressure to said cylinders.

4. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks rotatably mounted in therespectivesockets and held against radial movement therein, means for rotatingsaid blades including a piston mounted in one of said sockets formovement lengthwise thereof, a device connected with all of said bladesto cause them to rotate in unison, means for operatively connecting saidpiston with said blade connecting device to control the rotation of saidblades, and means for supplying fluid under pressure to the outer sideof said piston.

5. In a variable pitch propeller hcomprising va hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks mounted in the respective sockets forrotatory movement therein, uid operated means for rotating said bladesincluding pistons mounted in the respective sockets for movementlengthwise thereof, a device ro-v tive sockets for rotatory movementtherein, iiuid operated means for rotating said blades including acylinder in one of said sockets, a piston mounted in said cylinder formovement lengthwise thereof, a device connected with all of said bladesto rotate the same in unison, means for connecting said piston with saiddevice to actuate the same, a conduit extending through said piston tothe outer side thereof, and means for connecting said conduit with asource of supply for fluid under pressure.

7. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks mounted in the respective sockets forrotatory movement therein, i

fluid operated means for rotating said blades including a cylinder inone of said sockets, a piston mounted in said cylinder for movementlengthvvise thereof, a device connected with all of said blades torotate the same in unison, means for connecting said piston with saiddevice to actuate the same, a conduit rigidly mounted in said hub andextending through said piston to the outer side thereof, said pistonbeing slidable on said conduit, and means for ,connecting said conduitwith a source of supply for fluid under pressure.

8. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks mounted in tberespective sockets forrotatory movement therein, iiuid operated means for rotating said bladesincluding cylinders in the respective sockets, pistons mounted in therespective cylinders for movement lengthwise oi said sockets, a devicerotatably mounted in said hub and connected with all of said blades tocause them to-rotate in unison, means for connecting each of saidpistons with said rotatable device, a conduit extending through eachpiston to the outer portion of its cylinder, said piston being slidablymounted on said conduit and said hub having passageways connected withthe respective conduits, and means for connecting said passageways witha source of supply for iluid under pressure.

9. In av variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality Yof bladesockets,

and blades having shanks mounted in the respective sockets for rotatorymovement therein, at

least one of said shanks having a cylinder within the same, a pistonmounted in said cylinder for movement lengthwise of said shank,means forconnecting said piston with at least one of said blades to control therotatory movement ofthe latter, and means for supplying fluid underpressure to said cylinder on the outer side of said piston.

10. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks mounted in the respective sockets forrotatory movement therein, each of said shanks having a longitudinalcylinder Within the same, pistons mounted for reciprocatory movement inthe respective cylinders, means for connecting said pistons with saidblades to control the rotatory movement of the latter, and means forsupplying iiuid under pressure to said cylinders on the outer sides ofsaid pistons.

11. In a variable pitch propeller comprising a hub having means forconnecting the same with a shaft and having a plurality of bladesockets, and blades having shanks mounted in the respective sockets forrotatory movement therein, each of said shanks having a longitudinalcylinder within the same, pistons mounted for reciprocatory movement inthe respective cylinders, a device connected with all of said shanks tocause said blades to rotate in unison, means for connecting each pistonwith said device to control the rotation of said blades, and means forsupplying fluid under pressure to said cylinders on the outer sides ofsaid pistons. v

12. In a variable pitch propeller, a hub having means for connecting itwith a shaft and having a plurality of blade sockets, blades havingtubular shanks mounted in the respective blade sockets for rotatorymovement therein, a pinion secured to each blade shank, a gear rotatablymounted in said hub and meshing with each of said pinions, a cylinder ineach tubular shank, a piston mounted for reciprocatory movement in eachcylinder, connecting rods operatively connecting the respective pistonswith said gear, and means for supplying uid under pressure to saidcylinders.

blade sockets for rotatory movement therein, a i

cylinder mounted in the shank of each blade, pistons mounted in saidcylinders for movement lengthwise ofthe respective shanks, a deviceconnected with said blades to cause them to rotate in unison, means forconnecting each piston with said device to control the rotation of saidblades, conduits carried by said hub and extending through said pistonsto the outer portions o f the respective cylinders, said' hub havingpassageways connected with the respective conduits and extending to theexterior of said hub, and means for connecting said passageways with asource of supply for fluid under` pressure.

14. In a controllable pitch propeller, the combination of a hub, apropeller-blade rotatably mounted in the hub for pitch-variation, acylinder in the blade, a weight and piston mounted in the cylinder forradial movement by centrifugal force, and connected to rotate the bladefor pitch-variation, and means for shifting the pistonto shift theweight against centrifugal force.

15. In a controllable pitch propeller, the combination of a hub, apropeller blade rotatably mounted in the hub for pitch-variation, acylinder in the shank of the blade, a combined Weight and piston movablein the cylinder, movableA by centrifugal force, and connected to rotatethe blade for pitch-variation, and means for delivering iluid underpressure into the cyly inder to shift the piston and weight against theaction of centrifugal force.

16. In a controllable pitch propeller, the combination of a hub, apropeller blade rotatably mounted in the hub for pitch variation andagainst radial movement, a weight movably mounted in the blade andmovable by centrifugal force, means operable by the weight for rotatingthe blade to change its pitch in one direction, and fluid-pressure meansfor shifting the weight against centrifugal force and for rotating theblade in the opposite direction.

17. In a controllable pitch propeller, the combination of a hub, apropeller blade rotatably mounted in the hub for pitch variation andagainst radial movement, a weight movably mounted in the blade andmovable by centrifugal force, means operable by the Weight for rotatingthe blade to change its pitch`in one direction, and 1fluid-pressuremeans for shifting the weight against centrifugal force and for rotatingthe blade in the opposite direction, comprising a duct for iluid whichextends through the weight.

18. In a controllable pitch propeller, the com-l` bination of a hub, apropeller blade rotatably ing the blade to change its pitch in theotherr direction.

SAMUEL M. ALIRED.

